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From:   <yongqiang.niu@mediatek.com>
To:     <ck.hu@mediatek.com>, <p.zabel@pengutronix.de>,
        <robh+dt@kernel.org>, <matthias.bgg@gmail.com>
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        <dri-devel@lists.freedesktop.org>, <devicetree@vger.kernel.org>,
        <linux-kernel@vger.kernel.org>,
        <linux-arm-kernel@lists.infradead.org>,
        <linux-mediatek@lists.infradead.org>, <Bibby.Hsieh@mediatek.com>,
        <yt.shen@mediatek.com>, Yongqiang Niu <yongqiang.niu@mediatek.com>
Subject: [PATCH v2 24/25] drm/mediatek: respect page offset for PRIME mmap calls
Date:   Wed, 27 Mar 2019 14:19:20 +0800
Message-ID: <1553667561-25447-25-git-send-email-yongqiang.niu@mediatek.com>
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From: Yongqiang Niu <yongqiang.niu@mediatek.com>

Respect page offset for PRIME mmap calls

Signed-off-by: Yongqiang Niu <yongqiang.niu@mediatek.com>
---
 drivers/gpu/drm/mediatek/mtk_drm_gem.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/mediatek/mtk_drm_gem.c b/drivers/gpu/drm/mediatek/mtk_drm_gem.c
index c230237..524e494 100644
--- a/drivers/gpu/drm/mediatek/mtk_drm_gem.c
+++ b/drivers/gpu/drm/mediatek/mtk_drm_gem.c
@@ -144,7 +144,6 @@ static int mtk_drm_gem_object_mmap(struct drm_gem_object *obj,
 	 * VM_PFNMAP flag that was set by drm_gem_mmap_obj()/drm_gem_mmap().
 	 */
 	vma->vm_flags &= ~VM_PFNMAP;
-	vma->vm_pgoff = 0;
 
 	ret = dma_mmap_attrs(priv->dma_dev, vma, mtk_gem->cookie,
 			     mtk_gem->dma_addr, obj->size, mtk_gem->dma_attrs);
@@ -183,6 +182,12 @@ int mtk_drm_gem_mmap(struct file *filp, struct vm_area_struct *vma)
 
 	obj = vma->vm_private_data;
 
+	/*
+	 * Set vm_pgoff (used as a fake buffer offset by DRM) to 0 and map the
+	 * whole buffer from the start.
+	 */
+	vma->vm_pgoff = 0;
+
 	return mtk_drm_gem_object_mmap(obj, vma);
 }
 
-- 
1.8.1.1.dirty